PROJECTSUMMARY/ABSTRACT CongenitalHeartDisease(CHD)isthemostcommonbirthdefectaffectingapproximately1%ofalllivebirthsin theUSandisoneoftheleadingcausesofinfantmortality.AsevereformofCHDcanresultfromheterotaxy,a disorder of Left-Right (LR) patterning, during embryonic development. A recent genetic analysis of heterotaxy patientsidentifiedanovelCHDcandidategene,LRPPRC.LRPPRCencodesamitochondrialmRNAstabilizer which is critical for oxidative (aerobic) metabolism in the mitochondria. However, it has no known role in LR patterningorembryonicdevelopment.Usingdifferentknockdown/knockoutstrategiesinthehigh-throughputhu- man disease model, Xenopus, loss of lrpprc leads to LR patterning defects that recapitulate the patient?s phenotype.Theoverallgoalofthisproposalistoinvestigatethemolecularmechanismbywhichlrpprc affectsLRpatterningandheartdevelopmentintheXenopus(frog)modelsystemanddeterminehowits roleinmitochondrialmetabolismrelatestotheregulationofearlyembryonicdevelopment.Thefirstaim will determine the required role of lrpprc during embryonic patterning by using loss of function experiments to assesschangesinleft-rightanddorsal-ventralpatterningmarkersduringtheLRpatterningcascadeandearlier, atgastrulation.Thesecondaimwillinvestigatethemechanismbywhichlrpprcregulatesembryonicpatterning;? specifically, experiments will determine if the protein?s known mitochondrial function is important for its role in LRpatterningandcardiacdevelopment.Byattemptingtophenocopyleft-rightanddorsal-ventralpatterningde- fects through knockdown of other key OXPHOS regulatory proteins, performing real-time analysis of O2 consumption(oxidativemetabolism)andglycolysisduringkeydevelopmentalevents,andconfirmingthatLrpprc isrequiredinthemitochondriaduringearlydevelopment,experimentsinthisaimwillbetterdefiningtherelation- shipsbetweenlrpprc,metabolism,andearlyembryonicpatterninganddevelopment.Altogether,thisprojectwill improveourunderstandingofcardiacdevelopmentandtheroleoflrpprcandmitochondrialmetabolisminthe pathogenesisofCHD.Inthefuture,thiswillbenefitgenetictestingandcounseling,aswellasimproveoutcomes inCHDbecausetreatmentscanbetailoredtogenotyperatherthansolelyonCHDphenotype.Inaddition,this applicationdetailstheapplicant?strainingplanincludingresearchmentorship,advancedcoursework,trainingin new techniques, and the development of skills in scientific professionalism, writing, and presentation of data. The research and training outlined in this application will prepare the applicant to pursue a career performing patient-drivenresearchasanindependentresearchscientist.